Connector assembly for a coaxial cable

ABSTRACT

In a coaxial cable having a hollow inner-conductor, a connector assembly is provided for electromagnetically connecting the hollow inner-conductor and outer-conductor of the coaxial cable to a standard connector. In one disclosed embodiment, the connector assembly is formed from a body having an axial opening extending therethrough and an outer conductor contact portion. A dielectric cylinder is disposed within the axial opening of the body of the outer-conductor contact, the dielectric cylinder is provided with an axial opening extending therethrough. The assembly is further formed from an inner-conductor contact having a nose portion, a bridge portion adjacent to said nose portion, a shoulder portion adjacent to said bridge portion, a pin portion adjacent to said shoulder portion, wherein the bridge portion has a diameter which is smaller than the shoulder portion and the nose portion so as to define a groove therebetween and wherein the pin portion of the inner-conductor contact is disposed within the axial opening of the dielectric cylinder. A radial spring contact resides within the groove. The connector assembly of the present invention provides the advantage of allowing the inner-conductor contact to be installed in the body prior to connecting the assembly to the cable which reduces the chance of inner-conductor contact misalignment, among other things. The spring contact insures good electrical connection between the inner-conductor and the inner-conductor contact.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to connectors for coaxialcables, and more particularly, to connectors for coaxial cables havingcorrugated hollow inner-conductors.

2. Description of the Prior Art

A coaxial cable is typically terminated by a connector assembly whichmakes contact with both the inner-conductor and outer-conductor of thecable. Such a connector assembly provides a means for connecting thecable to another device. The connector assembly usually has anouter-conductor contact and an inner-conductor contact. Normally, theinner-conductor contact is first attached to the inner-conductor andthen the outer-conductor contact is attached to the outer-conductor.During attachment of the outer-conductor contact, the inner-conductorcontact is positioned within the outer-conductor contact so that theinner-conductor contact is supported therein. Under this assemblyprocedure, axial misalignment of the inner-conductor contact can resultcausing poor electrical performance, among other things. To reduce thepossibility of such misalignment, some prior art connector assembliesutilize two mating parts to connect the inner-conductor to the connectorassembly; one part is installed in the inner-conductor and the otherpart is affixed to the outer-conductor contact. By using two matingparts to connect the inner-conductor to the connector assembly,misalignment problems are reduced but not eliminated. Also, one problemwith the connector assembly design having a two mating partinner-conductor contact is that more parts and assembly time arerequired, which increases the costs of using and manufacturing such aconnector assembly.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide acoaxial cable connector assembly for connecting a coaxial cable toanother connector.

It is also an object of the present invention to provide a connectorassembly with a minimum number of parts.

It is a further object of the present invention to reduceinner-conductor misalignment problems.

It is still a further object of the present invention to provide aconnector assembly which permits accurate location of theinner-conductor relative to the body of the outer-conductor.

The foregoing objectives are realized by the connector assembly of thepresent invention which includes an inner-conductor contact having anose portion, a bridge portion adjacent to said nose portion, a shoulderportion adjacent to said bridge portion, a pin portion adjacent to saidshoulder portion, wherein the bridge portion has a diameter which issmaller than the shoulder portion and the nose portion so as to define agroove therebetween. A spring contact means resides within the groove ofthe inner-conductor contact to provide electrical contact between theinner-conductor and the inner-conductor contact when the connectorassembly is connected to a coaxial cable.

Other objects and advantages of the present invention will becomeapparent to those skilled in the art from the following detaileddescription read in conjunction with the attached drawings and claimsappended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings, not drawn to scale, include:

FIG. 1 which is a cross-sectional view of a coaxial cable, springcontact and body of the present invention having outer and innerconductor contacts in an assembled state;

FIG. 2A, which is a cross-sectional view of the inner-conductor contact;

FIG. 2B which is a cross sectional view of the spring contact and bodyof a first embodiment;

FIG. 3A which shows a front view of the spring contact;

FIG. 3B, which is a partial sectional view of the spring contact;

FIG. 4 which is a cross-sectional view of the body, spring contact andfillet of a second embodiment; and

FIG. 5 which is a cross-sectional view of the body and spring contact ofa third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus of the present invention may be used for connectingcoaxial cables to other cables or devices such as antennas and the like.Turning now to the drawings, in FIG. 1 there is shown a typical coaxialcable 10 having a helically corrugated inner-conductor 11 concentricallyspaced from center line A--A, an outer-conductor 12 disposed about theinner-conductor 11 and concentrically spaced from center line A--A. Thespace between the inner-conductor 11 and the outer-conductor 12 isfilled by a dielectric spacer 13. As FIG. 1 further illustrates, thehelically corrugated inner-conductor has a root diameter Dr, a walldiameter Dw and a corrugation depth Cd, which is half the differencebetween the wall diameter Dw and the root diameter Dr. As those skilledin the art will appreciate, coaxial cable connectors are normallyaffixed to a cable by a two step process wherein in the first step, aninner-conductor contact is attached to the inner-conductor and then anouter-conductor contact is attached to the outer-conductor. While theouter-conductor contact is being attached, care must be taken to avoidmisalignment of the inner-conductor contact which is usually held, afterassembly, within the body of the outer-conductor contact. The connectorassembly of the present invention, which will now be described, issuitable for making an electrical connection with both theouter-conductor and the inner-conductor at substantially the same time,thereby reducing, if not eliminating, the potential for misalignment ofthe inner-conductor contact.

As shown in FIGS. 1, 2A and 2B, a first embodiment of the connectorassembly of the present invention includes an inner-conductor contact 19(FIG. 2A) which has a nose portion 22, a narrow bridge portion 23, ashoulder portion 24, and a pin portion 25. The narrow bridge portion 23located between the nose and shoulder portions forms a groove in which aradial coil spring contact 28 resides. The purpose of the nose portion22 of the inner-conductor contact 19 is to center the contact 19 in theinner-conductor 11. In the case where the inner-conductor 11 iscorrugated, as shown in FIG. 1, the nose prevents the spring contact 28from forcing the inner-conductor contact 19 and the body 20 out of axialalignment with the inner-conductor 11. The diameter of the nose portion22 is selected so as to be less than the root diameter Dr of theinner-conductor 11, but large enough to prevent the spring contact 28from moving over the nose portion 22 and off the inner-conductor contact19 during removal of the body 20 from the cable 10. If theinner-conductor 11 is helically corrugated, the length L of the noseportion 22 is preferably at least as long as one pitch P of thecorrugation in order to properly center the inner-conductor contact 19and the body 20 during installation of the body 20 to the cable 10.

As shown in FIG. 2A, adjacent to the nose portion 22 is the bridgeportion 23 which has a diameter Db small enough to prevent the springcontact 28, having a similar inside diameter Dsi, from moving over thenose portion 22 and off the inner-conductor contact 19 during removal ofthe body 20 from the cable 10. Diameter Db is made large enough toassure electrical contact between the spring contact 28 and theinner-conductor 11, and between the spring contact 28 and the bridgeportion 23 and/or the shoulder portion 24 when the inner-conductorcontact 19 is inserted in the inner-conductor 11.

Moving to the left in FIG. 2A along the inner-conductor contact 19, theshoulder portion 24 is located adjacent to the bridge portion 23 at anend opposite of the nose portion 22. The shoulder portion diameter Dshis made sufficiently large to prevent the spring contact 28 from movingover the shoulder portion 24. As stated above, the nose portion 22,bridge portion 23 and shoulder portion 24 define a groove within whichthe spring contact 28 resides.

Adjacent to the shoulder portion 24 is the pin portion 25. The pinportion 25 is formed to suit the particular device (not shown) to beconnected to the body 20. In the embodiment shown in FIG. 2B, the end ofthe pin portion 25 which is not in contact with the shoulder portion isformed according to the requirements of a Din-type standard connector21, but may be formed to the specifications of a different type ofconnector. The pin portion 25, shoulder portion 24, and bridge portion23 and nose portion 22 are constructed from a conductive material.

A dielectric cylinder 26, made from a dielectric material (such aspolytetrafluoroethylene) having an axial opening therethrough isdisposed over the pin portion 25 for the purpose of insulating theinner-conductor contact 19 from the outer-conductor contact 27. Thedielectric cylinder 26 may be press-fit onto the pin portion 25 as shownin FIG. 2. As shown in FIGS. 1 and 2, a barb 37 and pin abutment 42prevent the pin portion 25 from moving with respect to the dielectriccylinder 26 disposed thereover.

The connector assembly of the present invention further includes acylindrically shaped body 20 having an outer-conductor contact portion27 and an axial opening therethrough. The dielectric cylinder 26disposed over the pin portion of the inner-conductor contact 19 ispositioned within opening in the body 20. In order to provide a tightseal between the body 20 and the dielectric cylinder 26, a gasket 36 isprovided between the body 20 to prevent moisture from entering theinner-conductor 11. As shown in FIGS. 1, 2A and 2B, a dielectricabutment 43 and the gasket 36 prevent the dielectric cylinder 26 frommoving with respect to the body. Once the dielectric cylinder 26 ispositioned within the opening in the body, the connector assembly of thepresent invention is ready to be attached to the coaxial cable.

Attachment of the connector to the cable is made by attaching the outerconductor contact 27 to threads 15 of a standard backnut 14. The backnut14 is prevented from slipping over the end of the cable by a splitferrule 17. Ordinarily, an O-ring seal 16 is positioned between thebacknut 14 and the outer-conductor 12 to seal out moisture, dirt andother contaminants.

As shown in FIG. 1, the outer-conductor contact 27 is threaded into thebacknut 14, the body 20 holds the pin portion 25, shoulder portion 24,bridge portion 23 and nose portion 22 of the inner-conductor contact 19radially and axially in place relative to the body 20. In order toreduce noise due to intermittent contact in the signal being transmittedby the inner-conductor 11 to the contact 19, the axial position of theinner-conductor contact 19 is fixed relative to the outer-conductorcontact 27 to assure that electromagnetic contact is made betweeninner-conductor contact 19 and the inner-conductor 11 only through thespring contact 28 and not directly with the shoulder portion 24.

Although FIG. 1 shows an outer-conductor contact 27 having externalthreads suitable for engaging the internal threads of the backnut 14,the mechanism incorporated into the outer-conductor contact 27 toconnect the outer-conductor contact 27 to the backnut 14 may varyaccording to the connecting means provided by the backnut 14.

FIGS. 3A and 3B show the over-all diameter Dso, coil height Ch and wirediameter Dwire of the spring contact 28, all three of which can beadjusted to suit the particular type of inner-conductor 11 used. Forexample, if the inner-conductor 11 is helically corrugated, the over-alldiameter Dso, coil height Ch and wire diameter Dwire are preferablyselected to allow the spring contact 28 to sufficiently compress inorder to contact the root diameter Dr of the corrugated inner-conductor11, and to allow the spring contact 28 to have sufficient contact forcewhere the spring contact 28 contacts the wall diameter Dw of theinner-conductor 11.

A second embodiment is depicted in FIG. 4, which differs from theembodiment shown in FIGS. 2A and 2B in that a fillet 38 has been addedat the corner between the bridge portion 23 and the shoulder portion 24.A third embodiment is illustrated in FIG. 5, wherein instead of adding afillet as in the second embodiment, the body 20 has been formed in sucha manner that the inner-conductor contact 19 has the same cross sectionas the second embodiment. The second and third embodiments provide acurved transition 29 between the bridge portion 23 and the shoulderportion 24 resulting in better electromagnetic contact between thespring contact 28 and the inner-conductor contact 19 because the springcontact will tend to be pushed towards the shoulder when theinner-conductor contact is inserted into the inner-conductor.

The body 20 generally shown in FIGS. 1, 2A and 2B has a Din-typestandard connector 21 suitable for connecting the body 20 to a matingDin-type connector (not shown). The present invention is not limited tothe use of a Din-type standard connector; other types of connectors maybe substituted to accommodate different requirements.

As can be seen from the foregoing detailed description of the preferredembodiments of the invention, the body 20 provides a means ofelectromagnetically connecting the hollow inner-conductor 11 andouter-conductor 12 of a coaxial cable 10 while reducing the chance ofaxial misalignment because the inner-conductor contact is alreadyinstalled in the body prior to the attachment of the connector to thecable. In addition, the body 20 described herein reduces the number ofparts required to connect a coaxial cable 10; fewer parts reducesassembly time and reduces the chance that essential parts will be lost.Finally, although FIG. 1 depicts the present invention in conjunctionwith a helically corrugated inner-conductor, the present invention willwork equally well with inner-conductors having other corrugationpatterns, or inner-conductors having a smooth inner surface.

Although the present invention has been described with respect to one ormore particular embodiments of the apparatus, it will be understood thatother embodiments of the present invention may be made without departingfrom the spirit and scope of the present invention. Hence, the presentinvention is deemed limited only by the appended claims and thereasonable interpretation thereof.

What is claimed is:
 1. A connector assembly for a coaxial cable having ahollow inner-conductor and an outer-conductor, the connector assemblycomprising:a body having an axial opening extending therethrough and anouter conductor contact portion for providing electrical contact withthe outer-conductor; a dielectric cylinder disposed within the axialopening of the body of the outer-conductor contact, the dielectriccylinder further having an axial opening extending therethrough; aninner-conductor contact having a nose portion at one end, a bridgeportion adjacent to said nose portion, a shoulder portion adjacent tosaid bridge portion, and a pin portion at an opposite end adjacent tosaid shoulder portion, wherein the bridge portion has a diameter whichis smaller than the shoulder portion and the nose portion so as todefine a groove therebetween and wherein at least a part of the pinportion of the inner-conductor contact is disposed within the axialopening of the dielectric cylinder; and a spring contact means residingwithin the groove of the inner-conductor contact for providingelectrical contact between the inner conductor and the inner conductorcontact.
 2. The connector assembly of claim 1, wherein the springcontact means is a radially compressible coil spring having inner andouter diameters sufficient to permit the radially compressible coilspring to touch both the bridge portion and the inner-conductor when thenose portion of the inner-conductor contact is inserted into theinner-conductor.
 3. The connector assembly of claim 1 wherein the bridgeportion and the shoulder portion form a corner and wherein a fillet isplaced over the corner.
 4. An inner-conductor contact assembly for usein a coaxial cable connector assembly, the inner conductor contactassembly comprising:an inner-conductor contact having a nose portion atone end, a bridge portion adjacent to said nose portion, a shoulderportion adjacent to said bridge portion, and a pin portion at anopposite end adjacent to said shoulder portion, wherein the bridgeportion has a diameter which is smaller than the shoulder portion andthe nose portion so as to define a groove therebetween; and a springcontact means residing within the groove of the inner-conductor contactfor providing electrical contact between the inner conductor and theinner conductor contact.
 5. The connecting member of claim 4, whereinthe spring contact means is a radially compressible spring having innerand outer diameters sufficient to permit the spring to touch both thebridge portion and the inner-conductor when the nose portion of theinner conductor connector is inserted in the inner-conductor.
 6. Theconnecting member of claim 4 further comprising a fillet added at acorner created by said bridge portion and said shoulder portion so.
 7. Aconnector assembly for a coaxial cable having a hollow inner-conductorand an outer-conductor, the connector assembly comprising:means forelectrically contacting the outer-conductor, the means having an axialopening therein; an inner-conductor contact having a nose portion at oneend, a bridge portion adjacent to said nose portion, a shoulder portionadjacent to said bridge portion, and a pin portion at an opposite endadjacent to said shoulder portion, wherein the bridge portion has adiameter which is smaller than the shoulder portion and the nose portionso as to define a groove therebetween; a spring contact means residingwithin the groove of the inner-conductor contact for providingelectrical contact between the inner conductor and the inner conductorcontact; and means for insulating the inner conductor contact from themeans for contacting the outer-conductor, the means being disposedwithin the axial opening in the outer-conductor contacting means anddisposed about at least part of the pin portion of the inner-conductorcontact.
 8. The connector of claim 7, wherein the spring contact meansis a radially compressible spring having inner and outer diameterssufficient to permit the spring to touch both the bridge portion and theinner-conductor when the nose portion of the inner conductor contact isinserted in the inner-conductor.
 9. The connector of claim 7 furthercomprising a fillet added at a corner created by said bridge portion andsaid shoulder portion so.